In this study, SRI proposes to develop new tissue-equivalent (TE) materials exhibiting ultrasonic energy-absorption coefficients and thermal transport properties corresponding to subcutaneous fat, skeletal muscle, and normal and cancerous liver. These TE materials will then be used to fabricate ultrasound phantoms in various configurations suitable for testing ultrasound transucers designed for hyperthermia therapy of tumors in humans. Temporal and spatial temperature profiles in large muscles of live pigs will be compared with those produced by the same transducer in phantoms made in geometrical imitation of the pigs' anatomy. Configurations will include layered fat and skeletal muscle, and a deep blood vessel with lumenal perfusion, and a large bone with perfused marrow, both embedded in TE soft tissue. In the second year, SRI will develop techniques for distributed perfusion of at least two separate compartments of the phantoms to simulate tissue blood flow, including vasodilation in response to hyperthermia. Phantoms with distributed perfusion will be configured to simulate a large blood vessel and a large bond embedded in skeletal muscle beneath subcutaneous fat, and a tumor embedded in soft tissue. SRI will design and construct a microcomputer-based temperature-monitoring and flow-control system to obtain temperature profiles and control perfusion. The resulting phantoms and new knowledge will also facilitate validation of computer models of hyperthermia and treatment planning.